Promoting photocatalytic hydrogen evolution rates in layered graphitic carbon nitride through integrated non-noble CoB co-catalyst
Suraj Gupta, Chayathorn Prapaitrakool, B.R. Bhagat, C. S. Yeh, Alpa Dashora, Akawat Sirisuk, N. Patel, Nina Daneu, Andraž Kocjan, Matjaž Spreitzer, Jeffrey C.S. Wu, Marjeta Maček Kržmanc
Abstract
Despite being one of the most widely studied metal-free semiconductors, graphitic carbon-nitride (gC3N4) shows meaningful photocatalytic activities only when loaded with noble-metal co-catalysts. The present work reports an alternative to noble metals in the form of cobalt boride (CoB) co-catalyst that can be easily integrated within the gC3N4 framework with facile fabrication strategies. The optimized CoB-gC3N4 composite showed ∼60 times higher hydrogen generation rate compared to bare gC3N4 nanosheets, with good stability. Detailed morphological, structural, chemical, electrochemical and spectroscopic investigations revealed the key aspects of CoB-gC3N4 composite that unanimously led to higher photocatalytic activity. Computational investigations not only corroborated the experimental results but also established that the surface Co and B sites in CoB provided the most energetically favoured sites for hydrogen evolution reaction. Based on the experimental and computational investigations, a generic reaction mechanism was formulated that will prove as a guiding light for future studies on similar photocatalytic systems.